The weights wtc, wjc, wvc, wdvc are fine-tuned using an optimization method which involves a series of simple metrics that compare a synthesized utterance to a set of test utterances.
A language was not a set of actual utterances produced by speakers but the underlying principles or rules that made it possible for speakers to produce such utterances and, moreover, an unlimited number of them.
Relative features in contrast to absolute features, which represent directly calculable information, are defined by the relationship between an utterance and a set of selected datum utterances.
Such processes work well for generating a core set of utterances or vocal expressions but are less effective in situations where a particular vocabulary is needed (for example, terms related directly to a user's interest in horse riding).
Clearly, some features of aphasias are a direct causal consequence of neuronal dysfunction, and may restrict patients to a very limited set of utterances, a single recurring utterance in the extreme, or to phonologically distorted jargon.
We verified this by computing the distributions of the Euclidean distance between neighbouring frames and frames taken at random time distances of >20 frames in a set of 100 randomly selected utterances.
However, in the total variability space estimation, a given speaker's entire set of utterances is regarded as having been produced by different speakers.
If we suppose that a given target language's entire set of utterances is regarded as having been produced by different languages, a common pool of hidden variables acts as basis factors and represents the utterances from different languages.
We estimate the language total variability space by using the dataset shown in Section 5, and we suppose that a given target language's entire set of utterances is regarded as having been belonging to different language.
Zellig Harris, an archetypal Externalist, is explicit that the reason for not regarding the set of utterances as finite concerns the elegance of the resulting grammar: "If we were to insist on a finite language, we would have to include in our grammar several highly arbitrary and numerical conditions" (Harris 1957: 208).
